JP2023161321A - electric motor - Google Patents

Abstract

To provide an electric motor that can utilize the magnetic flux of a permanent magnet as effectively as possible and efficiently increase torque without size increase.SOLUTION: An electric motor comprises: a stator 8 that has a stator core 20 composed of a stator core main body 21 and teeth 22; coils 24 that are wound around the teeth 22; a shaft 31; a rotor core 32 that is fixed to the shaft 31 and has a rotor core main body 37 having the axis of rotation of the shaft 31 as a radial center; main magnets 33 that are arranged on an outer peripheral surface of the rotor core main body 37; and a sub magnet 34 that is arranged on at least one end face of both end faces in an axial direction of the rotor core main body 37. The main magnets 33 each have an overhang part 33g that projects outward in the axial direction beyond the at least one end face of both end faces in the axial direction of the rotor core main body 37. The sub magnet 34 is arranged on the inside in a radial direction of the overhang parts 33g.SELECTED DRAWING: Figure 3

Description

The present invention relates to electric motors.

Some electric motors include a stator having teeth around which coils are wound, and a rotor rotatably provided inside the stator in the radial direction. Slots are formed between teeth adjacent in the circumferential direction. A coil is wound around each tooth through this slot. The stator and rotor are formed by laminating electromagnetic steel plates in the direction of the rotational axis of the shaft (hereinafter simply referred to as the axial direction) or by press-molding soft magnetic powder.

Interlinkage magnetic flux is formed in the stator by supplying power to the coil. The rotor includes a shaft, a cylindrical rotor core that is fitted and fixed to the shaft, and a permanent magnet provided in the rotor core. Then, magnetic attraction and repulsion are generated between the interlinkage magnetic flux formed in the stator and the permanent magnets provided in the rotor core, and the rotor is continuously rotated.

Here, as a method of arranging permanent magnets on the rotor, there is a method of arranging permanent magnets on the outer peripheral surface of the rotor core (SPM: Surface Permanent Magnet). In order to increase effective magnetic flux and achieve high torque in this SPM type rotor, the axial length of the permanent magnets may be made longer than the axial length of the stator and rotor core.
By causing one axial end of the permanent magnet to protrude further axially outward than one axial end of the stator, the amount of effective magnetic flux of the rotor can be increased. Therefore, the interlinkage magnetic flux formed in the stator can be efficiently contributed to the rotational force of the rotor, and the electric motor can be made to have high torque.

JP 2019-187132 Publication

By the way, in the above-mentioned conventional technology, the magnetic flux on the radially outer surface of the one axial end of the permanent magnet that protrudes further axially outward than the one axial end of the rotor core contributes to the rotational force of the rotor. On the other hand, no rotor core exists on the radially inner surface of one axial end of the permanent magnet. Therefore, the magnetic flux on the radially inner surface of one axial end of the permanent magnet becomes mere leakage magnetic flux. As a result, the effective magnetic flux of the permanent magnet decreases, making it difficult to efficiently increase the torque of the electric motor.

Although it is conceivable to configure the rotor core to exist over the entire radially inner surface of the permanent magnet, iron loss will occur. Furthermore, one end of the permanent magnet in the axial direction leaks through the rotor core, so it is difficult to say that this is an effective solution.

Therefore, the present invention provides an electric motor that can utilize the magnetic flux of a permanent magnet to the maximum extent possible and efficiently achieve high torque.

In order to solve the above problems, in a first aspect of the present invention, an electric motor includes a stator core that includes an annular stator core body and a plurality of teeth that protrude radially inward from an inner circumferential surface of the stator core body. a stator having a stator, a coil wound around the teeth, a shaft rotating inside the stator core in the radial direction, and a rotor core having a rotor core body fixed to the shaft and having a rotation axis of the shaft as the center in the radial direction; a main magnet disposed on an outer circumferential surface of the rotor core body; and a sub magnet disposed on at least one end face of both end faces of the rotor core body in the direction of the rotation axis and having a sub magnet body; The magnet has an overhang portion that protrudes outward in the rotation axis direction from at least one end surface of the rotor core body, and the sub magnet body is disposed radially inside the overhang portion.

With this configuration, the magnetic flux flowing from the radially inner surface of the overhang portion can be held by the sub-magnet main body. Therefore, the magnetic flux of the main magnet can be utilized to the maximum extent possible, and the electric motor can be efficiently increased in torque.

In a second aspect of the present invention, in the electric motor of the first aspect, the sub-magnet main body has a polar orientation in which the magnetization direction generates a magnetic pole on an outer circumferential surface facing the overhang portion.

With this configuration, the magnetic flux flowing from one magnetic pole of the overhang portion through the radially inner surface can flow to the magnetic pole adjacent to the overhang portion via the sub magnet body. Therefore, generation of leakage magnetic flux of the main magnet can be reliably prevented, and the magnetic flux of the main magnet can be utilized as effectively as possible.

In a third aspect of the present invention, in the electric motor of the first aspect or the second aspect, the rotor core has a plurality of rotor salient poles formed to protrude radially outward from the outer peripheral surface of the rotor core main body, The main magnets are arranged between the rotor salient poles adjacent in the circumferential direction.

With this configuration, reluctance torque can be used, so the electric motor can be made to have a high torque even more efficiently.
By the way, since the stator has salient rotor poles, iron loss occurs in the stator due to the influence of magnetic flux flowing through the rotor salient poles. In such a configuration, if, for example, the axial length of the rotor core is made longer than the axial length of the stator, the influence of iron loss on the stator will increase. For this reason, the main magnet is provided with an overhang portion without increasing the axial length of the rotor core relative to the axial length of the stator. Thereby, the influence of iron loss on the stator due to the rotor core can also be reduced.

In a fourth aspect of the present invention, in the electric motor of the third aspect, the sub-magnet has a plurality of salient magnetic poles formed to protrude radially outward from the outer peripheral surface of the sub-magnet main body, and the plurality of The salient magnet poles are respectively arranged on end faces of the plurality of rotor salient poles in the direction of the rotation axis.

With this configuration, the sub magnet can be easily positioned using the salient magnetic poles. Since the volume of the sub-magnet is increased by the presence of the salient magnetic poles, the effective magnetic flux of the sub-magnet can be increased.
Moreover, the magnetic flux flowing from both circumferential side surfaces of one main magnet can be made to flow to the adjacent main magnet via the sub magnet. Therefore, in the rotor core having salient rotor poles, leakage magnetic flux from the main magnet can be reliably prevented from occurring, and the magnetic flux from the main magnet can be utilized as effectively as possible.

In a fifth aspect of the present invention, in the electric motor of the fourth aspect, the main magnet has a main magnet side surface formed on at least a portion including the radially inner side of both circumferential side surfaces, and the main magnet side surface is , extends along the circumferential side surface of the salient magnetic pole and faces the circumferential side surface of the salient magnetic pole in the circumferential direction, and the radially outer end surface of the salient magnetic pole is opposite to the main magnetic salient pole. It is located between the radially outer end of the magnet side surface and the radially outer end of the rotor salient pole.

With this configuration, the magnetic flux flowing from both circumferential sides of one main magnet can be reliably flowed to the adjacent main magnet via the sub magnet, without unnecessarily increasing the volume of the sub magnet. . Therefore, the manufacturing cost of the electric motor can be suppressed as much as possible.

In a sixth aspect of the present invention, in the electric motor according to any one of the first to fifth aspects, an end surface of the main magnet in the direction of the rotation axis and an outer end surface of the sub magnet in the direction of the rotation axis are , located on the same plane.

With this configuration, the magnetic flux of the main magnet can be more reliably and most effectively utilized. That is, for example, if both ends of the sub magnet in the rotation axis direction protrude outward in the rotation axis direction from both ends of the main magnet in the rotation axis direction, magnetic flux leaks from the protruding portions of the sub magnet. On the other hand, if, for example, both ends of the main magnet in the direction of the rotational axis protrude outward in the direction of the rotational axis than both ends of the submagnet in the direction of the rotational axis, the effect of the submagnet in suppressing the leakage magnetic flux of the main magnet decreases.

According to a seventh aspect of the present invention, in the electric motor according to any one of the first to sixth aspects, the stator core and the rotor core are formed by laminating a plurality of electromagnetic steel sheets in the direction of the rotation axis.

With this configuration, eddy current loss occurring in the stator core, teeth, and rotor core can be reduced, and iron loss can be reduced. Therefore, the electric motor can be efficiently increased in torque.

According to the present invention, it is possible to provide an electric motor that can utilize the magnetic flux of a permanent magnet to the maximum extent possible and efficiently achieve high torque.

FIG. 1 is a perspective view of a motor with a speed reducer in an embodiment of the present invention. 2 is a sectional view taken along line II-II in FIG. 1. FIG. 1 is a configuration diagram of a stator and a rotor in a first embodiment of the present invention. FIG. FIG. 2 is a plan view of the rotor according to the first embodiment of the present invention, viewed from the axial direction. It is an axial cross-sectional view of a rotor core, a main magnet, and a sub-magnet in a 1st embodiment of the present invention. FIG. 1 is an exploded perspective view of a rotor in a first embodiment of the present invention. FIG. 7 is a plan view of a rotor according to a second embodiment of the present invention, viewed from the axial direction. 8 is an enlarged view of part VIII in FIG. 7. FIG.

Next, embodiments of the present invention will be described based on the drawings.

<Motor with reducer>
FIG. 1 is a perspective view of a motor 1 with a reduction gear. FIG. 2 is a sectional view taken along line II-II in FIG.
The motor 1 with a reduction gear is used, for example, as a drive source for a wiper device of a vehicle.
As shown in FIGS. 1 and 2, the motor 1 with a speed reducer includes an electric motor 2, a speed reducer 3 that decelerates and outputs the rotation of the electric motor 2, and a controller 4 that controls the drive of the electric motor 2. , is provided.

In the following description, simply "axial direction" means a direction parallel to the central axis of the shaft 31 of the electric motor 2 (rotation axis C of the electric motor 2). The term "circumferential direction" simply means the circumferential direction (rotational direction) of the shaft 31. The term "radial direction" simply refers to the radial direction of the shaft 31 that is perpendicular to the axial direction and the circumferential direction.

<Electric motor>
The electric motor 2 includes a motor case 5, a cylindrical stator 8 housed in the motor case 5, and a rotor 9 provided inside the stator 8 in the radial direction and rotatable with respect to the stator 8. , is provided. The electric motor 2 is a so-called brushless motor that does not require brushes when supplying power to the stator 8.

<Motor case>
The motor case 5 is made of a material with excellent heat dissipation, such as die-cast aluminum. The motor case 5 includes a first motor case 6 and a second motor case 7, which are configured to be axially separable. The first motor case 6 and the second motor case 7 are each formed into a cylindrical shape with a bottom.
The first motor case 6 is integrally molded with the gear case 40 of the reduction unit 3 so that the bottom portion 10 is joined to the gear case 40 of the reduction unit 3 . A through hole 10a through which the shaft 31 of the rotor 9 is inserted is formed in the radial center of the bottom portion 10.

An outer flange portion 16 is formed in the opening 6a of the first motor case 6, and an outer flange portion 16 is formed in the opening 7a of the second motor case 7. A flange portion 17 is formed. These outer flange portions 16 and 17 are butted against each other to form a motor case 5 having an internal space. A stator 8 is arranged in the internal space of the motor case 5 so as to be fitted into the first motor case 6 and the second motor case 7 .

<Stator>
FIG. 3 shows the configuration of the stator 8 and rotor 9, and corresponds to a view seen from the axial direction.
As shown in FIGS. 2 and 3, the stator 8 includes a cylindrical stator core body 21 having a circular cross-sectional shape along the radial direction, and a plurality of stator core bodies 21 that protrude radially inward from the stator core body 21 (for example, in this embodiment). The stator core 20 has integrally molded teeth 22 (six in number). The stator core 20 is formed by laminating a plurality of electromagnetic steel plates 20p in the axial direction. The stator core 20 is not limited to being formed by laminating a plurality of electromagnetic steel sheets 20p in the axial direction, but may be formed by, for example, press-forming soft magnetic powder.

The teeth 22 are integrally molded with a tooth body 101 that protrudes from the inner circumferential surface of the stator core body 21 along the radial direction, and a flange portion 102 that extends along the circumferential direction from the radially inner end of the tooth body 101. It is. The flange portion 102 is formed to extend from the tooth body 101 on both sides in the circumferential direction. A slot 19 is formed between the flanges 102 adjacent in the circumferential direction.

The inner circumferential surface of the stator core body 21 and the teeth 22 are covered with an insulator 23 made of a resin having insulation properties. A coil 24 is wound around each tooth 22 from above this insulator 23. Each coil 24 generates interlinkage magnetic flux for rotating the rotor 9 by power supply from the controller section 4 .

[First embodiment]
<Rotor>
FIG. 4 is a plan view of the rotor 9 of the first embodiment viewed from the axial direction. FIG. 5 is an axial cross-sectional view of the rotor core 32, main magnet 33, and sub magnet 34 of the first embodiment. FIG. 6 is an exploded perspective view of the rotor 9 in the first embodiment.
As shown in FIGS. 2, 4 to 6, the rotor 9 is rotatably provided inside the stator 8 in the radial direction with a small gap therebetween.

The rotor 9 includes a shaft 31 integrally molded with a worm shaft 44 constituting the reduction unit 3, a rotor core 32 fitted and fixed to the shaft 31, and four main magnets 33 provided on an outer peripheral surface 32a of the rotor core 32. , two sub-magnets (sub-magnet bodies) 34 provided on both axial end faces 32b and 32c of the rotor core 32 (both axial end faces of the rotor core body 37). Thus, in the electric motor 2, the ratio of the number of magnetic poles of the main magnet 33 to the number of slots 19 (teeth 22) is 2:3.

The rotor core 32 is formed by laminating a plurality of electromagnetic steel plates 32p in the axial direction. The rotor core 32 is not limited to being formed by laminating a plurality of electromagnetic steel plates 32p in the axial direction, but may be formed by, for example, press-forming soft magnetic powder.
The rotor core 32 includes a cylindrical rotor core body 37 whose radial center is the axis (rotation axis C) of the shaft 31, and four rotor protrusions formed to protrude radially outward from an outer circumferential surface 37a of the rotor core body 37. The pole 35 is integrally molded. The outer peripheral surface 37a of the rotor core body 37 is the outer peripheral surface 32a of the rotor core 32.

A shaft insertion hole 37b that penetrates in the axial direction is formed in the radial center of the rotor core body 37. The shaft 31 is press-fitted into the shaft insertion hole 37b. The shaft 31 may be inserted into the shaft insertion hole 37b, and the rotor core 32 may be fixed to the shaft 31 using an adhesive or the like. Four escape grooves 37c extending radially outward are formed in the shaft insertion hole 37b.
Each escape groove 37c is formed across the entire axial direction of the rotor core body 37, and communicates with the shaft insertion hole 37b. The relief grooves 37c are arranged at equal intervals in the circumferential direction. Each relief groove 37c has a role of adjusting the strength of press-fitting the shaft 31 into the shaft insertion hole 37b, for example.

The four rotor salient poles 35 are arranged at equal intervals in the circumferential direction. Each rotor salient pole 35 is arranged on the same straight line as each relief groove 37c in the radial direction. The rotor salient poles 35 are formed to extend throughout the axial direction of the rotor core 32. The rotor salient poles 35 are formed so that both side surfaces 35a facing each other in the circumferential direction are parallel to each other. That is, the rotor salient poles 35 are formed so that the circumferential width dimension is uniform in the radial direction.

In the radially outer end 35b of the rotor salient pole 35, one groove 91 is formed in the circumferential center over the entire axial direction. The groove portion 91 is formed in a V-groove shape such that the groove width in the circumferential direction becomes gradually narrower toward the inside in the radial direction. Round chamfered portions 35c are formed at both corners of the groove portion 91 in the circumferential direction. The radially outermost end of the round chamfered portion 35c becomes the radially outer end 35b of the rotor salient pole 35.

The outer circumferential surface 32a (outer circumferential surface 37a) of the rotor core 32 formed in this manner and between two circumferentially adjacent rotor salient poles 35 are each configured as a magnet storage section 36. The main magnets 33 are arranged in each of these magnet storage parts 36, and are fixed to the rotor core 32 with, for example, an adhesive or the like.

The main magnet 33 is formed in a tile shape. More specifically, in the main magnet 33, the position of the arc center Co of the outer circumferential surface 33a on the radially outer side and the position of the arc center Ci of the inner circumferential surface 33b on the radially inner side coincide with each other. These arc centers Co and Ci are shifted from the rotation axis C toward the corresponding main magnet 33 in the radial direction. The diameter of the circle passing through the radially outermost part of the outer peripheral surface 33a of the main magnet 33 is the same as the diameter of the circle passing through the radially outer end 35b of the rotor salient pole 35.

The inner peripheral surface 33b of the main magnet 33 is in contact with the outer peripheral surface 37a of the rotor core body 37 (the outer peripheral surface 32a of the rotor core 32). Both side surfaces of the main magnet 33 in the circumferential direction include a main magnet side surface 33c located on the inner side in the radial direction, and an inclined surface 33d located on the outer side in the radial direction than the main magnet side surface 33c. The main magnet side surface 33c is formed along the side surface 35a of the rotor salient pole 35. In other words, the main magnet side surface 33c and the side surface 35a of the rotor salient pole 35 are substantially parallel. The main magnet side surface 33c and the inner circumferential surface 33b are smoothly connected via an arcuate surface 33e.

The inclined surface 33d is formed obliquely and flat so as to gradually move away from the side surface 35a of the rotor salient pole 35 in the circumferential direction as it goes radially outward from the connecting portion 33f with the main magnet side surface 33c. The connecting portion 33f is arranged slightly outward from the radial center of the rotor salient pole 35. In one main magnet 33, the inclined surfaces 33d on both sides in the circumferential direction are parallel to the straight line S connecting the circumferential middle part of the main magnet 33 and the rotation axis C. Therefore, the two inclined surfaces 33d are also parallel to each other.

The axial length L1 of the main magnet 33 is longer than the axial length L2 of the rotor core 32. That is, the main magnet 33 has two overhang parts 33g and 33h that protrude outward in the axial direction from both axial end surfaces 32b and 32c of the rotor core 32. In each overhang portion 33g, 33h, protrusion lengths L3, L4 from both axial end surfaces 32b, 32c of the corresponding rotor core 32 are the same. In the following description, these protrusion lengths L3 and L4 are referred to as axial lengths L3 and L4 of the overhang portions 33g and 33h.

Such a main magnet 33 is magnetized so that the orientation of magnetization (magnetic field) is parallel along the radial direction (thickness direction). The main magnets 33 are arranged so that the magnetic poles are alternated in the circumferential direction. Therefore, the rotor salient poles 35 of the rotor core 32 are located between the main magnets 33 adjacent in the circumferential direction, that is, at the boundary between magnetic poles (polar boundary).
As the main magnet 33, for example, a ferrite bond magnet is used. However, the main magnet 33 is not limited to this, and instead of the ferrite bond magnet, a ferrite sintered magnet, a neodymium bond magnet, a neodymium sintered magnet, or the like may be used.

The sub magnet 34 is disposed on the rotor core body 37 of both end surfaces 32b and 32c of the rotor core 32 in the axial direction. The sub magnet 34 is formed in an annular shape to correspond to the shape of the rotor core body 37. The outer diameter D1 of the sub magnet 34 is approximately the same as the outer diameter D2 of the rotor core body 37. Therefore, the sub magnet 34 is arranged radially inside the overhang parts 33g and 33h of the main magnet 33. The outer circumferential surface 34a of the sub-magnet 34 faces the overhang portions 33g and 33h in the radial direction. The outer peripheral surface 34a of the sub magnet 34 is in contact with the inner peripheral surface 33b of the main magnet 33 (overhang parts 33g, 33h).

The inner diameter D3 of the sub magnet 34 is slightly larger than the inner diameter D4 of the shaft insertion hole 37b of the rotor core body 37. The axial length (thickness) L5 of the sub magnet 34 is the same as the axial lengths L3, L4 of the overhang parts 33g, 33h of the main magnet 33. Therefore, both axial end surfaces 33i and 33j of the main magnet 33 and the axial outer end surface 34b of each sub-magnet 34 are located on the same plane. The outer end surface 34b of the sub-magnet 34 refers to the end surface of the sub-magnet 34 on the opposite side to the rotor core 32, of both end surfaces in the axial direction.

Such a sub-magnet 34 has a polar orientation in which the orientation of magnetization (magnetic field) generates a magnetic pole on the outer peripheral surface 34a (see arrow J in FIG. 4). The number of magnetic poles of the sub magnet 34 is the same as the number of magnetic poles of the main magnet 33 (the number of main magnets 33). That is, in this embodiment, since the main magnet 33 has four magnetic poles, the sub magnet 34 also has four magnetic poles. The position of each magnetic pole of the sub magnet 34 is a position facing the main magnet 33 in the radial direction. The magnetic pole on the outer peripheral surface 34a of the sub magnet 34 is the same as the magnetic pole on the outer peripheral surface 33a of the main magnet 33. In other words, the magnetic pole on the outer circumferential surface 34a of the sub magnet 34 is different from the magnetic pole on the inner circumferential surface 33b of the main magnet 33.

As the sub magnet 34, for example, a ferrite bond magnet is used. However, the present invention is not limited to this, and instead of the ferrite bonded magnet, a ferrite sintered magnet, a neodymium bonded magnet, a neodymium sintered magnet, or the like may be used as the sub magnet 34. The material of the sub magnet 34 may be different from that of the main magnet 33.

<Reduction section>
Returning to FIGS. 1 and 2, the speed reduction unit 3 includes a gear case 40 to which the motor case 5 is attached, and a worm speed reduction mechanism 41 housed within the gear case 40. The gear case 40 is made of a material with excellent heat dissipation, such as die-cast aluminum. Gear case 40 is formed into a box shape with an opening 40a on one side. Gear case 40 has a gear accommodating portion 42 that accommodates worm reduction mechanism 41 . An opening 43 is formed in the side wall 40b of the gear case 40 at a location where the first motor case 6 is integrally molded, which communicates the through hole 10a of the first motor case 6 with the gear accommodating portion 42. .

A cylindrical bearing boss 49 is provided protruding from the bottom wall 40c of the gear case 40. The bearing boss 49 is for rotatably supporting the output shaft 48 of the worm reduction mechanism 41. The bearing boss 49 is provided with a sliding bearing (not shown) on its inner peripheral surface. An O-ring (not shown) is attached to the inner peripheral edge of the tip of the bearing boss 49. This prevents dust and water from entering from the outside into the inside through the bearing boss 49. A plurality of ribs 52 are provided on the outer peripheral surface of the bearing boss 49. This ensures the rigidity of the bearing boss 49.

The worm reduction mechanism 41 accommodated in the gear accommodating portion 42 includes a worm shaft 44 and a worm wheel 45 meshed with the worm shaft 44 . The worm shaft 44 is arranged coaxially with the shaft 31 of the electric motor 2. The worm shaft 44 is rotatably supported at both ends by bearings 46 and 47 provided in the gear case 40. The end of the worm shaft 44 on the electric motor 2 side projects through the bearing 46 to the opening 43 of the gear case 40 . The end of this protruding worm shaft 44 and the end of the shaft 31 of the electric motor 2 are joined, so that the worm shaft 44 and the shaft 31 are integrated. The worm shaft 44 and the shaft 31 may be integrally formed by molding the worm shaft portion and the shaft portion from one base material.

A worm wheel 45 meshed with the worm shaft 44 is provided with an output shaft 48 at the radial center of the worm wheel 45 . The output shaft 48 is arranged coaxially with the rotational axis direction of the worm wheel 45. The output shaft 48 projects to the outside of the gear case 40 via a bearing boss 49 of the gear case 40 . A spline 48a is formed at the protruding tip of the output shaft 48 to be connected to an electrical component (not shown).

A sensor magnet (not shown) is provided at the radial center of the worm wheel 45 on the side opposite to the side from which the output shaft 48 projects. The sensor magnet constitutes one side of a rotational position detection section 60 that detects the rotational position of the worm wheel 45. The magnetic detection element 61 constituting the other part of the rotational position detection section 60 is provided in the controller section 4, which is disposed opposite to the worm wheel 45 on the sensor magnet side of the worm wheel 45 (on the opening 40a side of the gear case 40). There is.

<Controller section>
The controller unit 4 that controls the drive of the electric motor 2 includes a controller board 62 on which a magnetic detection element 61 is mounted, and a cover 63 provided to close the opening 40a of the gear case 40. . A controller board 62 is disposed opposite to the sensor magnet side of the worm wheel 45 (the opening 40a side of the gear case 40).

The controller board 62 is a so-called epoxy board on which a plurality of conductive patterns (not shown) are formed. The terminal portion of the coil 24 drawn out from the stator core 20 of the electric motor 2 is connected to the controller board 62, and the terminal (not shown) of the connector 11 provided on the cover 63 is electrically connected. .

In addition to the magnetic detection element 61, the controller board 62 is mounted with a power module (not shown) consisting of switching elements such as FETs (Field Effect Transistors) that control the current supplied to the coil 24. . A capacitor (not shown) and the like are mounted on the controller board 62 to smooth the voltage applied to the controller board 62.

The cover 63 that covers the controller board 62 configured in this way is made of resin. The cover 63 is formed to bulge slightly outward. The inner surface of the cover 63 is a controller accommodating portion 56 that accommodates the controller board 62 and the like.
The connector 11 is integrally molded on the outer periphery of the cover 63. A connector extending from an external power source (not shown) is fitted into the connector 11 . A controller board 62 is electrically connected to the terminals of the connector 11. As a result, power from the external power source is supplied to the controller board 62.

A fitting portion 81 that fits into the end of the side wall 40b of the gear case 40 is formed protruding from the opening edge of the cover 63. The fitting portion 81 is constituted by two walls 81a and 81b along the opening edge of the cover 63. The end of the side wall 40b of the gear case 40 is inserted (fitted) between these two walls 81a, 81b. As a result, a labyrinth portion 83 is formed between the gear case 40 and the cover 63. The labyrinth portion 83 prevents dust and water from entering between the gear case 40 and the cover 63. Gear case 40 and cover 63 are fixed by fastening bolts (not shown).

<Operation of motor with reducer>
Next, the operation of the motor 1 with a speed reducer will be explained.
In the motor 1 with a speed reducer, power supplied to the controller board 62 via the connector 11 is selectively supplied to each coil 24 of the electric motor 2 via a power module (not shown). Then, a predetermined interlinkage magnetic flux is formed in the stator 8 (teeth 22), and magnetic attractive force and repulsive force are generated between this interlinkage magnetic flux and the effective magnetic flux formed by the main magnet 33 of the rotor 9. This causes the rotor 9 to rotate continuously.

When the rotor 9 rotates, a worm shaft 44 integrated with the shaft 31 rotates, and a worm wheel 45 meshed with the worm shaft 44 also rotates. Then, the output shaft 48 connected to the worm wheel 45 rotates, and a desired electrical component (for example, a wiper drive device mounted on a vehicle) is driven.

The rotational position detection result of the worm wheel 45 detected by the magnetic detection element 61 mounted on the controller board 62 is output as a signal to an external device (not shown). In an external device (not shown), the switching timing of a switching element, etc. of a power module (not shown) is controlled based on the rotational position detection signal of the worm wheel 45, and drive control of the electric motor 2 is performed. The output of the drive signal of the power module and the drive control of the electric motor 2 may be performed by the controller section 4.

<Rotor action>
Next, the function of the rotor 9 will be explained.
The rotor 9 is a so-called SPM (Surface Permanent Magnet) rotor in which a main magnet 33 is arranged on the outer peripheral surface 32a of a rotor core 32. Therefore, the inductance value in the d-axis direction becomes small. In addition, the rotor 9 is provided with salient rotor poles 35 between the main magnets 33 adjacent in the circumferential direction. As a result, the inductance value in the q-axis direction due to the interlinkage magnetic flux of the stator 8 becomes larger than that in the case where the rotor salient poles 35 are not provided. In this way, the rotor 9 is rotated by also utilizing the difference in reluctance torque between the d-axis direction and the q-axis direction.

The main magnet 33 has two overhang parts 33g and 33h that protrude outward in the axial direction from both axial end faces 32b and 32c of the rotor core 32. Therefore, the amount of effective magnetic flux of the rotor 9 is increased.
Here, sub-magnets 34 are provided on both axial end faces 32b, 32c of the rotor core 32, respectively. The sub magnet 34 is arranged radially inside the overhang parts 33g and 33h. Therefore, the magnetic flux flowing from the inner circumferential surfaces 33b of the overhang parts 33g and 33h is held by the sub magnet 34.

At this time, the sub magnet 34 has a polar orientation in which the orientation of magnetization (magnetic field) generates a magnetic pole on the outer peripheral surface 34a. Therefore, the magnetic flux on the inner peripheral surface 33b of the overhang portions 33g and 33h of one main magnet 33 passes through the sub magnet 34 and flows from the north pole to the south pole (see arrow J in FIG. 4). Then, magnetic flux flows to the adjacent main magnet 33 (overhang portions 33g, 33h) in the circumferential direction. Therefore, generation of leakage magnetic flux of the main magnet 33 is prevented, and the magnetic flux of the main magnet 33 is utilized as effectively as possible.

Thus, in the first embodiment described above, the main magnet 33 has two overhang parts 33g and 33h that protrude outward in the axial direction from both axial end faces 32b and 32c of the rotor core 32. Furthermore, sub-magnets 34 are provided on both end surfaces 32b and 32c of the rotor core 32 in the axial direction, respectively. The sub magnet 34 is arranged radially inside the overhang parts 33g and 33h. Therefore, the magnetic flux flowing from the inner circumferential surfaces 33b of the overhang parts 33g and 33h can be held by the sub-magnet 34. Therefore, the magnetic flux of the main magnet 33 can be utilized as effectively as possible, and the electric motor 2 can be efficiently increased in torque.

The sub magnet 34 has a polar orientation in which the orientation of magnetization (magnetic field) generates a magnetic pole on the outer peripheral surface 34a. Therefore, the magnetic flux flowing from one overhang portion 33g, 33h via the inner circumferential surface 33b can smoothly flow to the adjacent overhang portion 33g, 33h in the circumferential direction via the sub magnet 34. Therefore, generation of leakage magnetic flux of the main magnet 33 can be reliably prevented, and the magnetic flux of the main magnet 33 can be utilized as effectively as possible.

For example, when the orientation of the magnetization (magnetic field) in the sub-magnet 34 is set to radial orientation, as shown by the magnetization (magnetic field) orientation J' indicated by the two-dot chain line in FIGS. 4 and 5, the sub-magnet 34 Although the magnetic flux of the magnet 33 can be maintained to some extent, leakage magnetic flux is generated on the inner peripheral surface side of the sub-magnet 34. Therefore, by making the orientation of the magnetization (magnetic field) in the sub magnet 34 polar, the leakage flux of the main magnet 33 can be more reliably prevented from occurring, and the magnetic flux of the main magnet 33 can be utilized more effectively.

The rotor core 32 has four salient rotor poles 35 formed to protrude radially outward from the outer peripheral surface 37a of the rotor core body 37. Therefore, the reluctance torque can be utilized, so that the electric motor 2 can be made to have a high torque even more efficiently.

By the way, since the rotor salient pole 35 is provided, iron loss occurs in the stator core 20 due to the influence of the magnetic flux flowing through the rotor salient pole 35. In such a configuration, if, for example, the axial length L2 of the rotor core 32 is made longer than the axial length of the stator core 20, the influence of iron loss on the stator core 20 will increase. For this reason, the overhang portions 33g and 33h are provided in the main magnet 33 without making the axial length L2 of the rotor core 32 longer than the axial length of the stator core 20. Thereby, the influence of iron loss on the stator core 20 due to the rotor core 32 can also be reduced.

Both end surfaces 33i and 33j in the axial direction of the main magnet 33 and the outer end surface 34b in the axial direction of each sub-magnet 34 are located on the same plane. Therefore, the magnetic flux of the main magnet 33 can be more reliably and most effectively utilized. That is, for example, if the axially outer end surface 34b of each sub-magnet 34 protrudes further in the axial direction than the axially opposite end surfaces 33i, 33j of the main magnet 33, leakage magnetic flux is generated from the protruding portion of the sub-magnet 34. It will happen. On the other hand, if, for example, both axial end surfaces 33i and 33j of the main magnet 33 protrude further axially outward than the axial outer end surface 34b of each sub-magnet 34, the leakage magnetic flux of the main magnet 33 due to the sub-magnet 34 is reduced. The suppressing effect will be reduced.

The stator core 20 of the stator 8 is formed by laminating a plurality of electromagnetic steel plates 20p in the axial direction. The rotor core 32 of the rotor 9 is formed by laminating a plurality of electromagnetic steel plates 32p in the axial direction. Therefore, eddy current loss occurring in stator core 20 and rotor core 32 can be reduced, and iron loss can be reduced. Therefore, the electric motor 2 can be efficiently increased in torque.

The main magnet 33 is magnetized so that the orientation of magnetization (magnetic field) is parallel along the radial direction (thickness direction). Therefore, compared to the case where the orientation of the magnetization (magnetic field) in the main magnet 33 is radial orientation, cogging of the electric motor 2 can be suppressed and the effective magnetic flux of the rotor 9 can be increased.

Further, the position of the arc center Co of the outer peripheral surface 33a of the main magnet 33 is shifted from the rotation axis C toward the corresponding main magnet 33 in the radial direction. Therefore, the distance between the main magnet 33 and the stator core 20 (teeth 22) gradually increases from the middle of the circumference of the main magnet 33 toward both side surfaces in the circumferential direction. Thereby, the magnetic poles of the rotor 9 can be smoothly switched with respect to the stator 8, and cogging of the electric motor 2 can be further suppressed.

Since the electric motor 2 can be efficiently increased to high torque, goal 7 of the Sustainable Development Goals (SDGs) led by the United Nations, ``Ensure access to affordable, reliable, sustainable, and modern energy for all'', is achieved. , and Goal 9: “Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation.”

In the first embodiment described above, the rotor core 32 has four rotor salient poles 35 formed to protrude radially outward from the outer circumferential surface 37a of the rotor core body 37. The case has been described in which four main magnets 33 are provided so as to be arranged between each of the rotor salient poles 35 adjacent in the circumferential direction. However, the invention is not limited to this, and the rotor core 32 may not have the rotor salient poles 35. In this case, the main magnet 33 may be a cylindrical so-called ring magnet.

[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. 2, 5, and 6, and based on FIGS. 7 and 8. Aspects that are the same as those in the first embodiment are given the same reference numerals and description thereof will be omitted.
FIG. 7 is a plan view of the rotor 209 of the second embodiment viewed from the axial direction. FIG. 7 corresponds to FIG. 4 described above. FIG. 8 is an enlarged view of section VIII in FIG. 7.
As shown in FIGS. 2, 7, and 8, in the second embodiment, the motor 1 with a reduction gear includes an electric motor 202, a reduction unit 3 that decelerates and outputs the rotation of the electric motor 202, and an electric motor 202. The basic configuration, including the controller section 4 that performs drive control, is the same as that of the first embodiment described above.

As shown in FIGS. 7 and 8, the difference between the first embodiment and the second embodiment is the shape of the sub magnet 34 in the rotor 9 of the first embodiment, and the shape of the sub magnet 34 in the rotor 209 of the second embodiment. 234 is different in shape.
More specifically, the sub magnet 234 includes an annular sub magnet main body 71 and four salient magnetic poles 72 formed to protrude radially outward from the outer peripheral surface 71a of the sub magnet main body 71, which are integrally molded. It is what was done.

The sub-magnet main body 71 is arranged on the rotor core main body 37 (see FIG. 5) among both end surfaces 32b and 32c of the rotor core 32 in the axial direction. The shape of the sub-magnet main body 71 is the same as the shape of the sub-magnet 34 in the first embodiment. That is, the sub magnet main body 71 is formed in an annular shape so as to correspond to the shape of the rotor core main body 37. The outer diameter D21 of the sub-magnet body 71 is approximately the same as the outer diameter D2 (see FIG. 6) of the rotor core body 37. Therefore, the sub-magnet main body 71 is arranged radially inside the overhang parts 33g and 33h of the main magnet 33. The outer peripheral surface 71a of the sub-magnet main body 71 faces the overhang parts 33g and 33h in the radial direction. The outer peripheral surface 34a of the sub magnet 34 is in contact with the inner peripheral surface 33b of the main magnet 33 (overhang parts 33g, 33h).

The four magnetic salient poles 72 are arranged at equal intervals in the circumferential direction. Each of the magnetic salient poles 72 is arranged on the rotor salient pole 35 of both axial end surfaces 32 b and 32 c of the rotor core 32 . The magnetic salient pole 72 is formed so that both side surfaces 72a facing each other in the circumferential direction are parallel to each other. That is, the magnetic salient poles 72 are formed so that the circumferential width dimension is uniform in the radial direction. The circumferential width of the magnetic salient poles 72 is the same as the circumferential width of the rotor salient poles 35. Therefore, both side surfaces 72a of the salient magnet pole 72 are in contact with the main magnet side surface 33c of the main magnet 33.

A radially outer end surface 72b of the magnetic salient pole 72 is formed flat approximately along the circumferential direction. The outer end surface 72b of the salient magnet pole 72 is located between the connecting portion 33f of the main magnet 33 (radially outer end of the main magnet side surface 33c) and the outer end 35b of the salient rotor pole 35.
The orientation of magnetization (magnetic field) in such a sub-magnet 234 is also a polar orientation similarly to the sub-magnet 34 of the first embodiment (see arrow J in FIG. 7).

Therefore, according to the second embodiment described above, the same effects as those of the first embodiment described above are achieved. In addition, the sub magnet 234 has a salient magnetic pole 72 . Therefore, the sub magnet 234 can be easily positioned using the magnetic salient poles 72. Since the volume of the sub magnet 234 is increased by the presence of the salient magnetic poles 72, the effective magnetic flux of the sub magnet 234 can be increased.

Moreover, the magnetic flux flowing from one overhang part 33g, 33h via the inner circumferential surface 33b can smoothly flow to the adjacent overhang part 33g, 33h in the circumferential direction via the sub magnet 234. In particular, when the main magnets 33 are magnetized so that the orientation of magnetization (magnetic field) is parallel, the magnetic flux flowing from the main magnet side surface 33c of one main magnet 33 is circulated through the salient magnet poles 72. The water can flow smoothly to the adjacent overhang portions 33g and 33h in the direction (see arrow J in FIG. 7). Therefore, generation of leakage magnetic flux of the main magnet 33 can be reliably prevented, and the magnetic flux of the main magnet 33 can be utilized more effectively.

Note that when the orientation of the magnetization (magnetic field) in the main magnet 33 is radial orientation, the orientation on both sides of the main magnet 33 in the circumferential direction is approximately parallel to the side surface 72a of the salient magnet pole 72. Therefore, the flow of magnetic flux from both sides of the main magnet 33 in the circumferential direction to the salient magnet poles 72 is difficult to occur.

Here, the portion where the magnetic salient pole 72 and the overhang portions 33g, 33h come into contact is radially inner than the connecting portion 33f of the main magnet 33. In other words, the radially inner side of the salient magnetic pole 72 than the connecting portion 33f contributes to preventing the generation of leakage magnetic flux in the main magnet 33. In the second embodiment, the outer end surface 72b of the salient magnet pole 72 is located between the connecting portion 33f of the main magnet 33 and the outer end 35b of the salient rotor pole 35. Therefore, the magnetic flux flowing from both circumferential side surfaces of one main magnet 33 can be reliably flowed to the adjacent main magnet 33 via the sub magnet 234 without unnecessarily increasing the volume of the sub magnet 234. Therefore, the manufacturing cost of the electric motor 202 can be suppressed as much as possible.

The present invention is not limited to the above-described embodiments, but includes various modifications to the above-described embodiments without departing from the spirit of the present invention.
For example, in the embodiment described above, the case where the motor 1 with a speed reducer is used as a drive source for a wiper device of a vehicle has been described. However, the motor 1 with a speed reducer is not limited to this, and in addition to the wiper device, the motor 1 with a speed reducer can also be used as a drive source for electrical components installed in a vehicle (for example, a power window, a sunroof, an electric seat, etc.), and other devices. can be used for a variety of purposes.

In the above embodiment, the sub magnets 34 and 234 were described as being in contact with the overhang portions 33g and 33h of the main magnet 33. However, the present invention is not limited to this, and the contact may not be complete. Even if a minute gap is formed between the main magnet 33 and the sub magnets 34, 234 due to manufacturing errors in the main magnet 33 and the sub magnets 34, 234, the same effects as in the above embodiment can be achieved. This also applies when the rotor salient poles 35 and the main magnets 33 are not in complete contact.

In the above embodiment, the main magnet 33 has two overhang parts 33g and 33h that protrude outward in the axial direction from both end faces 32b and 32c of the rotor core 32 in the axial direction. A case has been described in which the sub magnets 34 and 234 are provided on both axial end surfaces 32b and 32c of the rotor core 32 (both axial end surfaces of the rotor core body 37), respectively. However, the invention is not limited to this, and the main magnet 33 may have an overhang portion that protrudes outward in the axial direction from at least one of the axial end surfaces 32b and 32c of the rotor core 32. . In this case, the sub-magnets 34, 234 need only be provided at locations where overhangs exist.

In the above-described embodiment, the case where the protrusion lengths L3 and L4 of each overhang portion 33g and 33h are the same has been described. However, the present invention is not limited to this, and the protruding lengths L3 and L4 of each overhang portion 33g and 33h may not be the same. In this case, it is desirable to change the axial length (thickness) L5 of the sub magnet 34 in accordance with the protruding lengths L3, L4 of each overhang portion 33g, 33h. It is desirable that both axial end surfaces 33i and 33j of the main magnet 33 and the axial outer end surface 34b of each sub-magnet 34 are located on the same plane.

In the above-described embodiment, both side surfaces of the main magnet 33 in the circumferential direction include a main magnet side surface 33c located on the inside in the radial direction, and an inclined surface 33d located on the outside in the radial direction from the main magnet side surface 33c. explained. The case has been described in which the connecting portion 33f between the main magnet side surface 33c and the inclined surface 33d is arranged slightly outside the radial center of the rotor salient pole 35. However, the present invention is not limited to this, and the position of the connecting portion 33f in the main magnet 33 can be set arbitrarily. Moreover, it is also possible to make the whole of both side surfaces of the main magnet 33 in the circumferential direction the main magnet side surfaces 33c.

In the above-described embodiment, the rotor core 32 has four rotor salient poles 35. The rotor 9 has four main magnets 33 and the number of magnetic poles is four. The stator core 20 has been described as having six teeth 22. However, the present invention is not limited to this, and the number of rotor salient poles 35, main magnets 33, and teeth 22 can be set arbitrarily. The number of magnetic poles of the sub magnet 34 may be changed to correspond to the number of magnetic poles of the main magnet 33 in the rotor 9.

DESCRIPTION OF SYMBOLS 1...Motor with reduction gear, 2...Electric motor, 3...Reduction part, 4...Controller part, 5...Motor case, 6...First motor case, 6a...Opening part, 7...Second motor case, 7a...Opening part , 8... Stator, 9... Rotor, 10... Bottom, 10a... Through hole, 11... Connector, 16... Outer flange, 17... Outer flange, 19... Slot, 20... Stator core, 20p... Electromagnetic steel plate, 21... Stator core Main body, 22... Teeth, 23... Insulator, 24... Coil, 31... Shaft, 32... Rotor core, 32a... Outer peripheral surface, 32b... End surface, 32c... End surface, 32p... Electromagnetic steel plate, 33... Main magnet, 33a... Outer peripheral surface, 33b...Inner peripheral surface, 33c...Main magnet side surface, 33d...Slanted surface, 33e...Circular surface, 33f...Connection part, 33g...Overhang part, 33h...Overhang part, 33i...End face, 33j...End face, 34...Secondary Magnet, 34a...outer peripheral surface, 34b...outer end surface, 35...rotor salient pole, 35a...side surface, 35b...outer end, 35c...round chamfer, 36...magnet storage section, 37...rotor core body, 37a...outer circumferential surface, 37b...Shaft insertion hole, 37c...Groove, 40...Gear case, 40a...Opening, 40b...Side wall, 40c...Bottom wall, 41...Worm reduction mechanism, 42...Gear accommodating part, 43...Opening, 44...Worm shaft , 45... Worm wheel, 46... Bearing, 47... Bearing, 48... Output shaft, 48a... Spline, 49... Bearing boss, 52... Rib, 56... Controller housing section, 60... Rotation position detection section, 61... Magnetic detection element , 62... Controller board, 63... Cover, 71... Sub-magnet main body, 71a... Outer peripheral surface, 72... Magnet salient pole, 72a... Side surface, 72b... Outer end surface, 81... Fitting portion, 81a... Wall, 81b... Wall, 83... Labyrinth part, 91... Groove part, 101... Teeth body, 102... Flange part, 202... Electric motor, 209... Rotor, 234... Sub-magnet

Claims (7)

a stator having a stator core including an annular stator core body and a plurality of teeth protruding radially inward from an inner circumferential surface of the stator core body;
a coil wound around the teeth;
a shaft rotating inside the stator core in the radial direction;
a rotor core having a rotor core body fixed to the shaft and centered in a radial direction on the rotational axis of the shaft;
a main magnet disposed on the outer peripheral surface of the rotor core body;
a sub-magnet disposed on at least one of both end faces of the rotor core main body in the direction of the rotation axis, and having a sub-magnet main body;
Equipped with
The main magnet has an overhang portion that protrudes outward in the rotation axis direction from at least one end surface of the rotor core body,
The electric motor is characterized in that the sub-magnet main body is disposed radially inside the overhang portion. The electric motor according to claim 1, wherein the sub-magnet main body has a polar orientation in which a magnetic pole is generated on an outer circumferential surface facing the overhang portion. The rotor core has a plurality of rotor salient poles formed to protrude radially outward from the outer peripheral surface of the rotor core main body,
The electric motor according to claim 1 or 2, wherein the main magnet is arranged between each of the rotor salient poles adjacent in the circumferential direction. The sub-magnet has a plurality of salient magnetic poles formed to protrude radially outward from the outer peripheral surface of the sub-magnet main body,
4. The electric motor according to claim 3, wherein the plurality of magnetic salient poles are respectively arranged on end faces of the plurality of rotor salient poles in the direction of the rotation axis. The main magnet has a main magnet side surface formed on at least a portion including the radially inner side of both circumferential side surfaces,
The main magnet side surface extends along the circumferential side surface of the salient magnetic pole, and faces the circumferential side surface of the salient magnetic pole in the circumferential direction,
5. The radially outer end face of the salient magnet pole is located between the radially outer end of the main magnet side surface and the radially outer end of the rotor salient pole. electric motor. The electric motor according to claim 1 or 2, wherein an end face of the main magnet in the direction of the rotation axis and an outer end face of the sub magnet in the direction of the rotation axis are located on the same plane. motor. The electric motor according to claim 1 or 2, wherein the stator core and the rotor core are formed by laminating a plurality of electromagnetic steel sheets in the direction of the rotation axis.

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